There's a good article about this:
https://www.datagubbe.se/stupidslow/
(previous discussion)
https://news.ycombinator.com/item?id=40604972
The Amiga feels fast because its slowness is predictable. Modern systems have unexpected slowness, and unexpected things are always more noticeable.
I had a sidecar with my Amiga 1000, which allowed you to use an XT MFM hard drive + controller card for the Amiga side. Once kickstart + the software loaded, it was incredibly fast. It was weird having a full IBM PC + Amiga in one conjoined machine.
But I agree that predictable slowness is a thing. One only need to discuss traffic jams vs a 20 minute car trip without them.